Charlie R. Pierce is a noted CCTV/surveillance expert and is a regular contributor to SecurityInfoWatch.com.
Tiwsted pair offers you the chance to pick up on existing wiring that may already be in buildings you're securing, but you'll need to use transmitters and receivers to adapt the signal to these lines.
Photo credit: Courtesy NVT
A full variety of products are available to connect your video system using fiber optics, allowing "wide open" speeds for video transmission.
Photo credit: Courtesy American Fibertek
Wireless systems mean you can instantly access video from the screen on your PDA or wireless-enabled laptop.
Photo credit: Charlie R. Pierce
Welcome to the next installment of going digital. I know, your probably wondering just how many installations to this series there could possibly be ... right? Hang tight, I just don't see an end close by, and you should never stop learning.
This time, we are going take a quick look at the various types or choices that we have for video transmission. I know, you are thinking that this is another article about coaxial cable or something along those old tired analog paths ... right? Sorry, I wouldn't be much of a friend if I put you back that many years. However, since most of the world is still using coaxial cable, it is only right that we at least review it. Then we will get to the juice.
Coaxial cable has been the primary source of our CCTV woes for over 50 years. But there is a misconception that what works for cable TV should work for CCTV. Wrong! Cable TV is frequency based, not video-based. Cable TV likes and requires cheap and inexpensive cable. CCTV, on the other hand, is a very sophisticated electronic signal and so requires special treatment. The coax that we use must have specific qualities or your images will suffer greatly. There are three things that you must pay attention to with the coax itself.
The first is the shield. The shield works because of the harmonics (frequency) of the video signal. If you use anything other than pure copper, the harmonic frequency base of the video signal will not be able to support the shield and you will or could have all sorts of problems. Therefore the shield should be braided copper or reverse foil over braided copper. Lastly, with the shield, you should have a 95% efficiency rating (ER).
The next portion of the coaxial cable is the dielectric. This too must be very specific. It should have an impedance of 75 ohms. This sets the speed of the cable or how far the video signal can travel before it starts to deteriorate. I don't care what material the dielectric is made of, as long as it is rated for seventy five ohms, but I will tell you that foam dielectric will give you the best performance.
Under the dielectric we have the center core. The center core, like the shield, must be 100 percent copper. It can be either solid or stranded. Stranded will give you better results. Stranded center cores are also flexible so they can be used in applications where the cable is being flexed, such as situations feeding into a camera housing that is mounted to a pan/tilt.
Once you have the proper cable, you must then fit the size to that application. If your runs are less than 750 feet, you should use an RG59/U. If you need to go up to 1,200 feet, you can use an RG6/U. Want to run up to 2,500 feet? You must use an RG11/U. The RG stands for "Real Good." The number represents the size of the cable and the slash U is the designator for Copper, CCTV coax.
From here you get into connectors. I'm not going there this week. I will tell you that the only thing you should be using is a three piece, crimp on connector. Anything else will give you problems. If not today, then it will cause problems next week sometime at two in the morning. Oh, yes, there's one last thing. If your center core is too big for the center tit of the connector, don't cut strands or whittle the center core down to size. Go get the connector that has the right inner diameter on the center tit to match the outer diameter of the center core of the coaxial cable that you are using.
The next two forms of transmission that come to mind are fiber optics and microwave. I could write volumes on these two transmission methods (and I have). However, for the sake of moving into new stuff, I will pass them by this week.
Right after that comes twisted pair. This stuff is great. Imagine using a good ol' twisted pair of copper wires to transmit the video signal. This type of wiring saves money, increases distance and performance. It can also be used with any analog or IP camera. The cost comes in with the transmitter (mounted at the camera via a direct connection or coaxial pigtail) and the receiver (mounted at the head end via a direct connection or a coaxial pigtail). However, the cost of the transmitter and receiver are usually off set by the reduction of cost in materials and labor.
Wouldn't it be nice to walk into a job (new or old) where the cable was already installed? Most large corporate or industrial buildings have the cable you need in place. I am speaking about Category 3 (Cat3) cabling. Telephone lines ... dead pairs ... unused pairs of wire that were installed with the building or the first phone systems. They run all over the place. Cat3 is a lower grade cable than Cat5, but it works on the same principals. It has fewer twists per inch and less quality. The maximum transmission rate is 15 megabits with a sixty percent load at 3,000 feet. That calculates out to roughly 8 megabits of transmission capability for video. Figuring at an average of 1 meg per converted analog camera and up to 1.75 meg per mega-pixel camera, you should be able to get away with four to eight cameras on a single pair. If you want to see twisted pair technology, then you can look up NVT. They do it very well. This is not to say that they are the only ones. Please don't take this as a political push. NVT comes to mind ... plus they've been doing twisted pair from the beginning. As a last note on Cat3, you can convert it to a simple network. Granted, not the biggest thing in the world, but look at the potentials.
Next on the list is Category 5 (Cat5) cabling. This is essentially Cat3 with more twists per inch, higher quality and a 100 megabit transmission rate with a 60% load. This leaves you about 60 megabits of usable carrier over 300 feet. This is or has become a very popular method of transmission and is fast intruding on Coaxial cable. However, you will not walk into the lost and forgotten telephone closets and find it installed in most buildings. You will need to install it yourself or jump onto the existing LAN. Cat5 is 10 times easier and more reliable than coaxial cable.
Next, fiber optics. I know, you think that I said I wouldn't write about fiber. I only said I wouldn't get all mushy and into a big discord. As it is, single mode fiber can be converted into a 1 gigabyte network. Using a 60 percent load factor, this means that you have the potential for about 600 megs of bandwidth to work with. The best part is that you can go up to 40 miles with an off the shelf system. That's all I'm saying now.
Wireless systems are becoming very popular. For general purposes, you can use public bands with no licensing or related issues. The key is to watch for potential interferences. It is possible for cell phones to be interfered with if you overpower an area. Equally, it is possible that your neighbor may install something that is wireless that interferes with your system or visa versa. Most wireless systems don't have a very good penetration capability and therefore get bogged down when going from floor to floor. Equally, if your wireless system doesn't have a good filtering system and advanced digital formatting, it is possible for echoes to cause you all sorts of problems.
For long shots outside, you can go into the real of using licensed bands. This is becoming very popular in many cities across the world. It allows you to set up master LAN systems that are able to be used by a multiple of groups for multiple purposes. Wireless opens up "Plug and Play" attitude. Find me a place to plug in my power (or a solar panel) and I have video on any PC, Laptop, or appropriate PDA with wireless capability. Wireless, for the most part is restricted to a 54 meg bandwidth with a 40 percent load factor. This leaves you with about 20 meg to work with, which is a very nice amount in most applications. Just figure an average of 1 meg or so per channel for video.
That takes up my space for this column. Next time we will look at the wide world of telephone lines and networks. We'll be asking what DSL lines are and they differ from T1 or T3 lines. It's really not that bad, but it helps to be able to speak with a bit of intelligence when you're thinking about uploading and downloading your systems. I'll see you in a couple of weeks. Meanwhile, you can find the voluminous writings I've done on these topics in my books and other stuff; just click over to www.ltctrainingcntr.com.
A PERSONAL REQUEST FOR HELP TO THE INDUSTRY
For the past 31 years, I have been bragging to friends and family about the security industry and it gifts to the general public. So I am now addressing that same industry, personally with a request for help.
In about six weeks, a small Catholic School on the lower west end of Davenport Iowa will be permanently closing its doors. Sadly, this is happening after 100 years of dedicated service to the education of children of all faiths. This is a school where my wife and her brothers, my three sons and a countless number of other folks that are close to me, have attended. This is a school where the teachers and staff have worked for below average wages and given from their hearts for as many as 25 years. Because we are a small parish and an equally small community, our staff was never afforded compensation or retirement benefits. They will be saying goodbye with nothing more in their pockets other than the fond memories and broken hearts that years educating others will create.
Several weeks ago, I helped to found a committee of parents, parishioners and friends of St. Alphonsus School. The committee's sole purpose is to raise money for an employee appreciation fund to help these departing employees. All costs involved with our project, including legal, financial, postage and marketing have been donated by a wide array of professionals in the area. This allows us to use almost 99 percent of all money raised toward our employees.
Since the funds we are trying to raise are beyond the capacity of our local area, each member of the committee has reached out to friends, neighbors, and fellow workers. I am reaching out to the security industry as a whole. I realize that the world is full of good causes and sad cases. I also realize that this cause does not warrant national attention, and yet here I am. I am not trying to save the world or prevent any major disasters. I am only reaching out to an industry that has given me so much. I am reaching out to you, as an individual or company, to ask you to reach into your heart and help us to say thank you to a small group of people, a group of folks, that just like you, have given so much from their hearts for so long. Please don't think that any donation is too small or to large. All donations are fully tax deductible for those that itemize their taxes. Unfortunately our time is very short as we must close our efforts as of June 1, 2005. I personally have pledged to match 1 percent of all funds raised up to the first $200,000.
Please help me in this worthy cause by sending a check or money order today. These should be made out to: St. Alphonsus Employee Appreciation Fund and sent to the same name at P.O. Box 163, Davenport, 52805.
Thank you, from my heart for whatever you are able to do to help us.
- signed, Charlie R. Pierce
About the Author: Richard R. "Charlie" Pierce has been an active member of the security industry since 1974. He is the founder and past president of LRC Electronics Company, a full service warranty/non-warranty repair center for CCTV equipment. In 1985, Charlie founded LeapFrog Training & Consulting (Formally LTC Training Center), a full service training center specializing in live seminars, video-format certification training programs, plain language technical manuals and educational support on CCTV. He is an active member of ASIS, ALAS, CANASA, NBFAA, NAAA and SIA. He is the recipient of numerous security industry awards, and is a regular contributor to Security Technology & Design magazine. Look for his columns to also appear regularly via SecurityInfoWatch.com and this website's e-newsletters. He can be contacted via email at email@example.com.